Combination of hydrogen and oxygen



grates COMBINATIQN OF HYDROGEN AND OXYGEN No Drawing. ApplicationFebruary 27, 1953 Serial No. 339,486

12 Ciaims. (Cl. 23-404) Our invention relates to an improved method ofcombining oxygen and hydrogen into water and more particularly to thecombination of these elements into water'in an aqueous solution thereof.

There are numerous instances in industry wherein hazardous quantities ofhydrogen gas, formed as reaction by-product or remaining as an excessmust be disposed of when it may be uneconomical to package the hydrogenfor utilization or sale. Such a problem may exist for example in theelectrolytic production of sodium or in the venting of excess hydrogenfrom numerous hydrogenation reactions. Furthermore, considerableinterest has been evidenced in the design and construction of watercooled and Water moderated nuclear reactors, including homogeneousreactors wherein the reactor fuel is in the form of an aqueous solutionsuch as a uranyl sulfate solution or an aqueous slurry such as a uraniumdioxide-water slurry. During the operation of these reactors, the wateris usually subjected to strong irradiation by gamma and beta rays,fission fragments and neutrons, with the resulting decomposition ofwater into oxygen, hydrogen and hydrogen peroxide. Although the waterdecomposes to a relatively minor extent only, even the small degree ofdecomposition thus far noted is of some concern to nuclear reactordesigners, for, the resulting amount of gas bubbling may create aserious pile control problem. In addition, an explosive mixture ofhydrogen and oxygen may accumulate, local hot spots may be producedleading to fusion of fuel elements, and corrosion of reactor materialsmay become accelerated. 1

Numerous attempts, therefore, have been made to rapidly and efiicientlydispose of hydrogen by combining same with oxygen to form water. Bothflame and catalytic recombination systems have been employed to combinethese gases, it usually being necessary to first collect the gasbubbles. Catalysts usually consisted of platinum, platinum-on-alumina,platinum-on-charcoal or silver. However, such systems were veryintricate and expensive and the conditions for safe and efiicientoperation were relatively critical. Furthermore, such solid catalystsWere subject to surface poisoning.

Reference is also made to co-pending patent application Serial No.233,118, filed June 22, 1951, by A. 0. Allen and C. J. Hochanadel,entitled Suppression of Water Decomposition, in which hydrogen andoxygen in aqueous solution are recombined to an unexpected degree bydissolving an additional small amount of hydrogen gas in the solution.However, in addition to the inconvenience inherent in maintaining a gasconcentration in an aqueous solution, this method is applicable only torelatively pure water rather than to aqueous ice solutions of variouscompounds, and is, therefore, rather limited in utility.

An object of our invention, therefore, is to provide an improved methodfor disposing of hydrogen.

Another object of our invention is to provide an improved method ofcombining hydrogen with oxygen.

Another object of our invention is to provide an improved method forrecombining hydrogen and oxygen formed in aqueous solutions by ionizingradiations.

Another object of our invention is to provide an improved method forcontinuously recombining hydrogen and oxygen which are being formed inaqueous solutions by nuclear reactor radiations.

Still another object of our invention is to provide a method forincreasing the operating safety of a nuclear reactor which uses water ascoolant, moderant, solvent, or component of a slurry.

Another object of our invention is to provide an improved method forcontinuously recombining hydrogen and oxygen which is being formed in anaqueous uranyl sulfate solution by nuclear reactor radiations.

Other objects and advantages of our invention will be apparent from thefollowing description.

In accordance with our invention, we find that hydrogen and oxygen maybe rapidly combined under greatly varying conditions by providing asmall amount of copper ions in an aqueous solution of said hydrogen andoxygen under superatmospheric pressure.

When employing our invention, the combining of hydrogen and oxygen isaccomplished homogeneously be fore bubbles are formed and, of particularimportance in a nuclear reactor, the heat of reaction is uniformlydissipated. There is, therefore, no localized heating as in the case ofthe prior art solid catalysts herein described. In addition, nuclearreactor power fluctuations due to erratic bubble dispersion and removalare eliminated.

Our method is generally applicable to the combining of hydrogen andoxygen in aqueous solutions under superatmospheric pressures andpreferably at temperatures of approximately 150 C. to approximately 450C. and pressures corresponding to these temperatures while best resultsappear to be obtainable at temperatures above about 250 C. Althoughcombination still takes place at temperatures even lower than 150 C., itmay be too slow for practical operation.

Copper ions may be provided in aqueous solutions by dissolving thereincopper values which are soluble in the specific solution being employed.Thus, for example, relatively soluble copper salts such as CuSO CuF andCu(NO may be satisfactorily employed. In an aqueous acidic solutionhaving dissolved therein a reactor fuel material, the copper ions couldbe provided by dissolving copper metal in the solution. However, theaddition of a soluble copper salt is generally preferred. To avoidintroducing additional impurities into aqueous homogeneous reactor fuelsolutions, it is also preferred to introduce the copper ion by means ofa copper salt whose anion is identical to the anion of the fuel compoundalready present. For example,if uranyl sulfate is employed in an aqueousfuel solution it may be preferable to add the I copper in the form ofcopper sulfate.

centration. Thus, the greater the copper concentration, the lower theequilibrium pressure. However, the amount of combination for any givencopper content is controlled by numerous variables such as pressure andtemperature. Thus, routine testing and experimentation may beadvantageous in determining the preferred amount of copper to be added.However, we generally find that only a slight concentration of copperion in aqueous solution effects almost complete combination: of hydrogenand oxygen dis.- solved therein. Suitable quantities of copper iondissolved in-aqueoussolution, for example, are from approximately 0.001molar to approximately 0.2 molar, while a concentration ofapproximately. 0.05 molar is generally preferred. Although other ions,primarily ions of the elements thallium, iron, chromium, tin, silver,iodine, titanium, molybdenum, tungsten, technetium, and manganese undersin ilar conditions may demonstrate some degree of success in effectingthe combination, copper appears uniquely superior to all of the manytested.

Our invention will be further illustrated by the following specificexamples.

, Example 1 illustrates a combination test performed in the absence ofcopper ions.

EXAMPLE I Hydrogen and oxygen were introduced into a stainless steelbomb above distilled water at pressures of 300 pounds per square inchand 600 pounds per square inch respectively, the temperature beingmaintained at 249 C. The change of pressure with time was tabulated inTable I as follows. pressure. minus steam pressure at the particulartemperature.

EXAMPLE H v The method of Example I was employed except that the waterwas made 0.04 molar in CuSO and the temperature was maintained at 239 C.The change of pressure with time was tabulated in Table H as follows:

Table 11 Time (hours): Corrected pressure (lbs/sq. in.) 647 0.50 292 Byconducting this example at a temperature lower than that employed inExample I, other conditions being equal, the efiectiveness of ourinvention was demonstrated even more strikingly than if performed at thehigher temperature, since lowering the temperature in the absence ofcatalyst would further inhibit the combination of H and 0 The efiect ofthe Cu ions is still sufiicient to overcome entirely this additionaldisadvantage as is obvious from a comparison of the data.

Example III illustrates a test in the absence of copper ion but in thepresence of uranyl sulfate.

EXAMPLE III The method of Example II was employed except that thedistilled water was replaced by an aqueous uranyl sulfate solutioncontaining 29.7 grams of uranium per liter, and the temperature wasmaintained at 290 C. The change of pressure with time was tabulated inTable III as follows:

The results here appear to indicate that the uranyl sulfate itself, ifpure, had some effect in catalyzingthe recombination of hydrogen andoxygen. However, the degree of the effect was insuflicient to solve thedecomposition problem in an adequate manner.

Example IV illustrates the effect of adding copper ion to an aqueousuranyl sulfate solution.

EXAMPLE IV The method of Example III was employed except that theaqueous uranyl sulfate solution was made 0.16 molar in copper sulfate.Thechange of pressure with time was.

tabulated in Table IV as followsz.

The corrected pressure is equal to the total I Table IV Time (hours):Corrected pressure (lbs/sq. in.) 0 112,0. /6 f 1/3 These resultsindicate that copper is outstandingly ef-.- fective in that its useresults in a recombination rate in, the neighborhood of 100,000 timesthat shown byv uranyl sulfate alone at the same temperature, as may becalculated from equilibrium constant data.

EXAMPLE V Three aqueous solutions in stainless steel bombs were placedin a nuclear reactor in a zone wherein the neutron flux was of the orderof 6X10 neutrons per square centimeter per second. The first solutioncontained 40 grams per liter uranyl sulfate, the second solution contained 40 grams per liter uranyl sulfate and was 0.00625 molar in coppersulfate and thethird solution contained 40 grams per liter uranylsulfate and was 0.009 molar in copper sulfate. The uranium wasenrichedto 93.2% in the 235 isotope. The samples were permitted to remain atvarious temperatures for a suflicient period of time for equilibriumpressures to be obtained. These pressures for each solution, inpounds'per square inch, are tabulated as follows:

1 Corrected equilibrium pressuresin p. s. i.

EXAMPLE v1 The method of Example V wasemployed except that an aqueoussolution 0.16 molar in-uranyl sulfate and 0.05 molar in copper sulfateWas employed, and the neutron fiux was of the order of 1X10. neutronsper square centimeter per second. The change of equilibrium pressurewith temperature is tabulated as follows:

' T able Vl Corrected pressure Temperature C.): (lbs/sq. in.)

It is noted from all the above examples that the presence of smallamounts of copper ions in the solutions described has a profoundlysignificant effect in displacing the H O 7 /2O ;f-H equilibrium stronglyin the direction of water formation with a resulting low equilibrium gaspressure.

It is to be understood of course that the above examples are merelyillustrative, and do not limit the scope of our invention, which shouldbe understood to be limited only as indicated by the appended claims.

We claim:

1. A method of combining hydrogen with oxygen which comprises providingcopper ions in an aqueous solution of said hydrogen and oxygen undersuperatmospheric pressure and at a temperature above approximately 150C.

2. A method of forming water from hydrogen and oxygen in aqueoussolution which comprises providing a small amount of copper ions in saidsolution at a temperature of approximately 150 C. to approximately 450C.

3. The method of claim 2 in which the temperature is above approximately250 C.

4. A method of forming water from hydrogen and oxygen in aqueoussolution which comprises providing said solution With copper ions in aconcentration of approximately 0.001 molar to approximately 0.2 molar ata temperature of approximately 150 C. to approximately 450 C.

5. A method for continuously recombining hydrogen and oxygen resultingfrom the subjection of an aqueous solution to ionizing radiations, whichcomprises providing a small amount of copper ion in said solution at atemperature above approximately C.

6. A method for continuously recombining hydrogen and oxygen resultingfrom the subjection of an aqueous solution to ionizing radiations whichcomprises providing said solutions with copper ions in a concentrationof approximately 0.001 molar to approximately 0.2 molar at a temperatureof approximately 150 C. to approximately 450 C.

7. The method of claim 6 in which the ionizing radiations are nuclearreactor radiations.

8. The method of claim 6 in which the ionizing radiations are fastneutrons.

9. The method of claim 6 in which the ionizing radiations are gammarays.

10. The method of claim 6 in which the ionizing radiations are fissionfragments.

11. A method for continuously recombining hydrogen and oxygen resultingfrom the subjection of an aqueous uranyl sulfate solution to nuclearreactor radiations which comprises providing a small amount of coppersulfate in said solution at a temperature above apporximately 150 C.

12. A method of continuously recombining hydrogen and oxygen resultingfrom the subjection of an aqueous uranyl sulfate solution to nuclearreactor radiations which comprises providing said solution with copperions in a concentration of approximately 0.05 molar at a temperatureabove approximately 250 C.

References Cited in the file of this patent AEC Document MDDC1056, June1947, declassified June 23, 1947, pages 1-ll.

Allen et al.: J. of Phy. Chem, vol. 56, pages 575 586, May 1952;received Feb. 25, 1952, and this date relied on to show prior knowledgeunder Sec. of the Atomic Energy Act of 1954.

1. A METHOD OF COMBINING HYDROGEN WITH OXYGEN WHICH COMPRISES PROVIDINGCOPPER IONS IN AN AQUEOUS SOLUTION OF SAID HYDROGEN AND OXYGEN UNDERSUPERATMOSPHERIC PRESSURE AND AT A TEMPERATURE ABOVE APPROXIMATELY150*C.